The present invention relates generally to creation and maintenance of multi-component fluids, and, especially, to adapters, adapter systems and methods of using adapters in connection with powered injectors for agitation of multi-component injection fluids.
In a number of medical procedures, it is desirable to inject a multi-component injection medium into a patient. An example of such a medical procedure is ultrasound imaging.
Ultrasound imaging creates images of the inside of the human body by broadcasting ultrasonic energy into the body and analyzing the reflected ultrasound energy. Differences in reflected energy (for example amplitude or frequency) appear as differences in gray scale or color on the output images. As with other medical imaging procedures, contrast-enhancing fluids (often referred to as contrast media) can be injected into the body to increase the difference in the reflected energy and thereby increase the contrast in the image viewed by the operator.
For ultrasonic imaging, the most common contrast media contain many small bubbles. The difference in density of bubbles when compared to water, and thus their difference in sound transmission, makes small gas bubbles excellent means for scattering ultrasound energy. Small solid particles can also serve to scatter ultrasonic energy. Such particles are typically on the order of 1 to 10 microns (that is, 10xe2x88x926 to 10xe2x88x925 meters) in diameter. These small particles can pass safely through the vascular bed.
Contrast media suitable for use in ultrasound are supplied in a number of forms. Some of these contrast media are powders to which liquid is added just before use. The powder particles cause a gas bubble to coalesce around them. The powder must be mixed with a liquid, and the mixture must be agitated with just the right amount of vigor to get the optimum creation of bubbles. Another type of contrast medium is a liquid that is agitated vigorously with air. There are no solid particles to act as nuclei, but the liquid is a mixture of several liquid components that make relatively stable small bubbles. A third type of contrast medium uses xe2x80x9chardxe2x80x9d spheres filled with a gas. These contrast media are typically supplied as a powder that is mixed with a liquid. The goal is to suspend the spheres in the liquid without breaking them. Even though such spheres have a shell that is hard compared to a liquid, they are very small and relatively fragile. It is also possible for the solid particles themselves to act to scatter ultrasonic energy, but the acoustical properties of the solid spheres are not as different from liquid as those of a gas, so the difference in reflected energy is not as strong.
After mixing/preparation as described above, the contrast medium is drawn into a syringe or other container for injection into the patient. Typically, the fluid is injected into a vein in the arm of the patient. The blood dilutes and carries the contrast medium throughout the body, including to the area of the body being imaged.
It is becoming more common for a microprocessor controlled powered injector to be used for injecting the contrast medium to maintain a consistent flow over a long time, thereby providing a consistent amount of contrast medium (number of particles) in the blood stream. If there are too few particles in a region of interest, for example, there is insufficient image contrast and the diagnosis cannot be made. If too many particles are present, too much energy is reflected, resulting in blooming or saturation of the ultrasound receiver.
Although a power injector can inject contrast medium at a constant flow rate, there must be a constant number of bubbles per volume of fluid injected to provide a constant image contrast. Because a gas is significantly less dense than water and other liquids, however, gas bubbles will rise in a liquid. The rate of rise is related to the diameter of the gas bubble. This density difference is useful to quickly separate large bubbles created during the initial mixing. However, the small bubbles desired for image enhancement will also rise slowly. Solid particles, on the other hand, tend to settle or sink because most solids are denser than water. Many minutes can elapse between the initial mixing of the contrast medium and the injection into the patient, and/or the injection itself may be several minutes in duration. Certain multi-component contrast media undergo significant separation after only a few minutes. If the concentration of particles changes over the volume of fluid, the image contrast will degrade.
The benefits of agitation of multi-component fluids to create, improve or maintain homogeneity via a number of techniques are discussed, for example, in U.S. patent application Ser. No. 09/267,237, filed Mar. 12, 1999, assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference. Likewise, Published PCT Application No. WO 99/27981 discloses powered injectors designed to agitate contrast medium to, for example, maintain suspension of media such as ultrasound bubbles and provides representative studies of the efficacy of those powered injectors.
It remains desirable to develop improved systems, devices and method to maintain multi-component contrast media in a mixed or homogeneous state throughout an injection proceeding. It is particularly desirable to develop such systems, devices and methods that are suitable for use with existing powered injectors and injector systems.
The present invention provides generally, devices, systems and methods for creating and/or agitating a multi-component medium (for example, an ultrasound contrast medium, a medicant including a suspended agent etc.) suitable for injection into a patient.
In one aspect, the present invention provides an adapter for use with a powered injector to impart agitating motion to a syringe, which is connectable to the powered injector. As used herein, the term xe2x80x9csyringexe2x80x9d refers to fluid containers from which a pressurized fluid can be ejected. Often a syringe includes a generally cylindrical barrel through which a piston or plunger is movable to aspirate fluid into the syringe and to eject pressurized fluid. As used herein, the term xe2x80x9cpowered injectorxe2x80x9d refers to any powered mechanism used to pressurize the contents of a syringe. Examples of powered injectors include, but are not limited to, MEDRAD PULSAR(copyright) injectors available from Medrad, Inc. of Indianola, Pa. and Harvard Apparatus syringe pumps available from Instech Laboratories, Inc. of Plymouth Meeting, Pa. Powered injectors typically include a drive member to impart motion to a plunger slidably disposed within the syringe.
The adapter includes an injector attachment mechanism to attach the adapter to the powered injector and a syringe interface to attach the syringe to the adapter. In many cases, the injector attachment mechanism of the adapter is preferably of the same type as an attachment mechanism on the syringe that is used to attach the syringe to a syringe interface on the injector. Likewise, the syringe interface on the adapter is preferably of the same type as the syringe interface on the powered injector. The adapter preferably further includes an intermediate drive member having a drive attachment to attach the intermediate drive member to the drive member of the powered injector and a plunger attachment member to attach the intermediate drive member to the syringe plunger. The intermediate drive member is operable to translate motion of the drive member of the powered injector to the syringe plunger. The adapter also includes at least one powered agitator to provide agitating motion to the syringe interface (and thereby to the syringe attached thereto).
As used herein, the term xe2x80x9cagitating motionxe2x80x9d refers generally to motion other than the reciprocal sliding motion of the syringe plunger and can, for example, include any number of types of motions suitable to cause mixing of fluid components within the syringe including, but not limited to, rotational motion, orbital motion and/or vibrational motion. In one embodiment, the adapter rotates the syringe interface to rotate the syringe about its longitudinal axis. The adapter can also or alternatively rotate the syringe interface to rotate the syringe about an axis perpendicular to its longitudinal axis. Likewise, the adapter can also or alternatively orbit the syringe interface about an orbital axis to orbit the syringe about the orbital axis.
The intermediate drive member can, for example, include a rigid and/or a flexible connector to facilitate agitating motion.
In one embodiment, the adapter includes a first hydraulic cylinder to which the injector attachment mechanism is connected. The first hydraulic cylinder is in fluid connection via at least one flexible line with a second hydraulic cylinder to which the syringe interface is connected.
In another embodiment, the adapter includes a motor and a drive belt in operative connection with the syringe interface. The motor can, for example, rotate the syringe interface via the drive belt to impart rotation of the syringe about its longitudinal axis, to impart rotation of the syringe about an axis generally perpendicular to its longitudinal axis or to impart orbital motion to the syringe. In one embodiment in which orbital motion is imparted to the syringe, the adapter includes a first section to which the injector attachment mechanism is connected and a second section to which the syringe interface is connected. The second section is connected to the first section at an angle so that the syringe interface orbits about an axis when the first section is rotate. The drive belt is preferably in operative connection with the first section to rotate the first section about its longitudinal axis.
In another aspect, the present invention provides a powered injector system including a powered injector having a drive member to impart motion to a syringe plunger slidably disposed in a syringe that is connectable to the powered injector and an adapter as described above to impart agitating motion to the syringe.
In still another aspect, the present invention provides a method of providing a powered injector or powered injector system with the capability to impart the agitating motion to a syringe, which is connectable to the powered injector. The method includes the step of: attaching an adapter as described above to the powered injector. The method preferably also includes the steps of attaching a syringe to the syringe interface and activating the powered agitator. The method can also include the step of sensing the syringe configuration of a syringe attached to the syringe interface. The powered agitator can, for example, be controlled in correspondence with the sensed syringe configuration. Likewise, the control of the injection via control of the powered injector drive member can be controlled in a manner consistent with sensed syringe configuration.
Unlike currently available agitation devices, systems and methods for agitating multi-component injection fluids, the adapters, systems and methods of the present invention do not require specific, dedicated and/or redesigned powered injectors. To the contrary, the adapters, systems and methods of the present invention can be used with virtually any currently available powered injector to add the capability to that injector to impart agitating motion to a syringe. The adapters, systems and methods of the present invention thereby provide a substantial improvement in the art. For example, operating personnel can continue to use existing powered injectors with which they have become acquainted, increasing operator efficiency and safety of operation as compared to deployment of a new injectors or injector systems. Moreover, the adapters of the present invention can provide cost savings as compared to deployment of new injectors or injector systems.